2024, 38(6): 631-643.
doi: 10.3969/j.issn.1007-2993.2024.06.001
Abstract:
The ground treatment techniques for the 9th National Geotechnical Engineering Records Conference were reviewed, and new techniques, digitalization, and intelligence for ground treatment applications were introduced. Furthermore, some directions were provided which should be strengthened in future research. Ground treatment faces the challenge of transitioning towards green, low-carbon, and intelligent solutions. Future development directions include utilizing BIM and big data to construct intelligent foundation design systems and treatment construction management systems. Application research in soft ground foundation treatment, settlement control, and MICP technology should be emphasized. It is necessary to prompt the integration of theoretical knowledge with practical experience and update relevant standards and specifications to better meet the needs of national construction projects.
The ground treatment techniques for the 9th National Geotechnical Engineering Records Conference were reviewed, and new techniques, digitalization, and intelligence for ground treatment applications were introduced. Furthermore, some directions were provided which should be strengthened in future research. Ground treatment faces the challenge of transitioning towards green, low-carbon, and intelligent solutions. Future development directions include utilizing BIM and big data to construct intelligent foundation design systems and treatment construction management systems. Application research in soft ground foundation treatment, settlement control, and MICP technology should be emphasized. It is necessary to prompt the integration of theoretical knowledge with practical experience and update relevant standards and specifications to better meet the needs of national construction projects.
2024, 38(6): 644-649.
doi: 10.3969/j.issn.1007-2993.2024.06.002
Abstract:
Combined with the major needs of digitalization and informatization construction in the engineering investigation industry, the current status and shortcomings of the digital technology for engineering investigation were systematically analyzed, the research on key technologies in the digital collection, integrated management, and collaborative application of investigation information was carried out, several research results with practical engineering application value were obtained. Taking the Dongzhuang Water Control Project as an example, through the application of the key technologies of air-ground integration digital engineering investigation, the work efficiency and achievement quality of water conservancy engineering investigation in the mountain canyon area were improved, this provides a reference for the geological work in large-scale, long-distance, and difficult areas in the field, and promoting the advancement of information technology in the investigation industry.
Combined with the major needs of digitalization and informatization construction in the engineering investigation industry, the current status and shortcomings of the digital technology for engineering investigation were systematically analyzed, the research on key technologies in the digital collection, integrated management, and collaborative application of investigation information was carried out, several research results with practical engineering application value were obtained. Taking the Dongzhuang Water Control Project as an example, through the application of the key technologies of air-ground integration digital engineering investigation, the work efficiency and achievement quality of water conservancy engineering investigation in the mountain canyon area were improved, this provides a reference for the geological work in large-scale, long-distance, and difficult areas in the field, and promoting the advancement of information technology in the investigation industry.
2024, 38(6): 650-654.
doi: 10.3969/j.issn.1007-2993.2024.06.003
Abstract:
According to the technical code for geotechnical bolt and shotcrete support engineering (GB 50086—2015), the checking calculation of anti-floating stability of anti-floating bolt as a whole can be known, the overall stability of the anti-floating anchor was related to the total weight of the soil (W), the self-weight of the structure, other permanent loads (G) and the buoyancy of the groundwater (Ff) in the scope of the anti-floating anchor under the foundation, the self-weight and other permanent loads (G) of the structure and the buoyancy of the groundwater (Ff) can be calculated by relevant regulations. The stress of the anti-floating anchor was analyzed, and the calculation formula of anti-floating stability checking of the anti-floating anchor was put forward according to the relevant codes.
According to the technical code for geotechnical bolt and shotcrete support engineering (GB 50086—2015), the checking calculation of anti-floating stability of anti-floating bolt as a whole can be known, the overall stability of the anti-floating anchor was related to the total weight of the soil (W), the self-weight of the structure, other permanent loads (G) and the buoyancy of the groundwater (Ff) in the scope of the anti-floating anchor under the foundation, the self-weight and other permanent loads (G) of the structure and the buoyancy of the groundwater (Ff) can be calculated by relevant regulations. The stress of the anti-floating anchor was analyzed, and the calculation formula of anti-floating stability checking of the anti-floating anchor was put forward according to the relevant codes.
2024, 38(6): 655-661.
doi: 10.3969/j.issn.1007-2993.2024.06.004
Abstract:
For pile+internal support, to reduce or avoid the use of side truss bracing and inclined bracing systems, a method of increasing the crown beam section was proposed to expand the main support spacing. This method can control the deformation of the foundation pit and ensure the safety and stability of the foundation pit. Based on the basic theory research of the design of the large crown beam, combined with the engineering case, the Lizheng software and MIDAS/GTS finite element software were used for calculation and analysis. The results indicate that the design of the large crown beam can effectively control the deformation of the foundation pit. By comparing and analyzing actual monitoring data, the feasibility and reliability of the design of the large crown beam have been verified. Adopting this support scheme can not only ensure the safety of the foundation pit itself but also ensure the normal use of surrounding buildings. Increasing the spacing between supports for earthwork and underground structure construction can shorten the project duration and reduce engineering costs, which has engineering application value.
For pile+internal support, to reduce or avoid the use of side truss bracing and inclined bracing systems, a method of increasing the crown beam section was proposed to expand the main support spacing. This method can control the deformation of the foundation pit and ensure the safety and stability of the foundation pit. Based on the basic theory research of the design of the large crown beam, combined with the engineering case, the Lizheng software and MIDAS/GTS finite element software were used for calculation and analysis. The results indicate that the design of the large crown beam can effectively control the deformation of the foundation pit. By comparing and analyzing actual monitoring data, the feasibility and reliability of the design of the large crown beam have been verified. Adopting this support scheme can not only ensure the safety of the foundation pit itself but also ensure the normal use of surrounding buildings. Increasing the spacing between supports for earthwork and underground structure construction can shorten the project duration and reduce engineering costs, which has engineering application value.
2024, 38(6): 662-671.
doi: 10.3969/j.issn.1007-2993.2024.06.005
Abstract:
The direct calibration of constitutive models requires that the model parameters have clear physical significance, which corresponds to the geometric interpretation of the testing data. However, for the complex constitutive models with multiple hyperparameters, the optimization technique shall be applied to calibrate those parameters. The particle swarm optimization (PSO) was utilized, which can calibrate the model parameters based on raw data of the stress-strain curves. Technical details of properly implementing the algorithm were illustrated, which focuses on the quantity of particles, and the data requirements for the von Wolfersdorff hypoplastic model and the Drucker-Prager elastoplastic model. Also, the behavior of the PSO algorithm in analyzing the real experimental data was discussed. Since the calculation of the error function is a summation, the stress integration can be terminated for those particles, whose error function has exceeded its historical optimum or reached an overflow state. The early-stopping mechanism was proved to significantly improve computation efficiency.
The direct calibration of constitutive models requires that the model parameters have clear physical significance, which corresponds to the geometric interpretation of the testing data. However, for the complex constitutive models with multiple hyperparameters, the optimization technique shall be applied to calibrate those parameters. The particle swarm optimization (PSO) was utilized, which can calibrate the model parameters based on raw data of the stress-strain curves. Technical details of properly implementing the algorithm were illustrated, which focuses on the quantity of particles, and the data requirements for the von Wolfersdorff hypoplastic model and the Drucker-Prager elastoplastic model. Also, the behavior of the PSO algorithm in analyzing the real experimental data was discussed. Since the calculation of the error function is a summation, the stress integration can be terminated for those particles, whose error function has exceeded its historical optimum or reached an overflow state. The early-stopping mechanism was proved to significantly improve computation efficiency.
2024, 38(6): 672-679.
doi: 10.3969/j.issn.1007-2993.2024.06.006
Abstract:
To determine the impact of pipe-jacking construction on the surrounding environment, engineering data was collected and combined with case monitoring results to study the mechanism and laws of surface and existing tunnel deformation caused by pipe-jacking construction. The conclusions are as follows: (1) The settlement law of the surface section conforms to the Peck formula, with an influence range of about 1.4~2.6 times the diameter of the top pipe. The surface deformation development curve is divided into two forms: "uplift first and then settlement" and "full settlement". (2) The overall uplift of existing tunnels presents a "reverse" Peck curve, and the uplift amount was affected by the stiffness of the existing tunnel and the magnitude of the disturbance it is subjected to. With the increase of time, the uplift amount first increases rapidly and then tends to stabilize. (3) Monitoring and analysis were conducted on the pipe-jacking project of the existing tunnel, and the deformation patterns of the surface and tunnel were basically consistent with existing research patterns. Several measures were taken to control the deformation of the surface and existing tunnel, with a maximum settlement of about 11 mm on the surface and a maximum uplift of about 1.6 mm on the existing tunnel. The research results can provide certain references for the design and construction of related pipe-jacking.
To determine the impact of pipe-jacking construction on the surrounding environment, engineering data was collected and combined with case monitoring results to study the mechanism and laws of surface and existing tunnel deformation caused by pipe-jacking construction. The conclusions are as follows: (1) The settlement law of the surface section conforms to the Peck formula, with an influence range of about 1.4~2.6 times the diameter of the top pipe. The surface deformation development curve is divided into two forms: "uplift first and then settlement" and "full settlement". (2) The overall uplift of existing tunnels presents a "reverse" Peck curve, and the uplift amount was affected by the stiffness of the existing tunnel and the magnitude of the disturbance it is subjected to. With the increase of time, the uplift amount first increases rapidly and then tends to stabilize. (3) Monitoring and analysis were conducted on the pipe-jacking project of the existing tunnel, and the deformation patterns of the surface and tunnel were basically consistent with existing research patterns. Several measures were taken to control the deformation of the surface and existing tunnel, with a maximum settlement of about 11 mm on the surface and a maximum uplift of about 1.6 mm on the existing tunnel. The research results can provide certain references for the design and construction of related pipe-jacking.
2024, 38(6): 680-691.
doi: 10.3969/j.issn.1007-2993.2024.06.007
Abstract:
Regarding the applicability of settlement-reducing piles in complex stratum conditions, the influence of factors such as the site condition and building type, maximum settlement control standard, and pile and soil stiffness distribution on the design of settlement-reducing piles based on a large number of practical engineering projects were discussed. The application criteria and design methods of settlement reducing pile as the optimization objective were proposed, and the rationality was verified by engineering cases. The results show that the settlement-reducing pile has good adaptability to various sites and building types. The important grade of the foundation, the bearing capacity of the foundation, and the stiffness distribution of the pile and soil are the key factors to determine its application. To save the amount of piles and ensure the overall safety of the foundation, it was recommended that the bearing capacity of the foundation in soft and hard soils should not be less than 0.5 and 0.65, respectively. Considering the contribution of raft-bearing capacity, the dimensionless influence coefficient of Gibson soil and layered soil was recommended not to be less than 2.3 and 1.5, respectively. Meeting the above requirements can be used as the premise to determine the applicability of the settlement-reducing pile.
Regarding the applicability of settlement-reducing piles in complex stratum conditions, the influence of factors such as the site condition and building type, maximum settlement control standard, and pile and soil stiffness distribution on the design of settlement-reducing piles based on a large number of practical engineering projects were discussed. The application criteria and design methods of settlement reducing pile as the optimization objective were proposed, and the rationality was verified by engineering cases. The results show that the settlement-reducing pile has good adaptability to various sites and building types. The important grade of the foundation, the bearing capacity of the foundation, and the stiffness distribution of the pile and soil are the key factors to determine its application. To save the amount of piles and ensure the overall safety of the foundation, it was recommended that the bearing capacity of the foundation in soft and hard soils should not be less than 0.5 and 0.65, respectively. Considering the contribution of raft-bearing capacity, the dimensionless influence coefficient of Gibson soil and layered soil was recommended not to be less than 2.3 and 1.5, respectively. Meeting the above requirements can be used as the premise to determine the applicability of the settlement-reducing pile.
2024, 38(6): 692-697.
doi: 10.3969/j.issn.1007-2993.2024.06.008
Abstract:
Under the action of groundwater, the surrounding rock of a loess tunnel will undergo varying degrees of softening, greatly weakening its strength, which brings many difficulties to the design and construction of the tunnel. Based on a loess tunnel in Longdong, different degrees of softening were set up, and finite element numerical simulation software was used to calculate and analyze the deformation of the tunnel surrounding rock and the stress changes of lining structure under different degrees of rock softening. At the same time, a comparative analysis was conducted on the on-site reinforcement measures after the softening of the surrounding rock and the lining structure of the enlarged arch foot. The results show that after the strong softening of the deeply buried loess tunnel, the settlement of the arch top increased by 271%, the uplift of the arch bottom increased by 283%, the horizontal convergence increased by 205%, and the maximum principal stress of the initial support increased by 107%. The most unfavorable stress position appeared at the arch shoulder. After adopting two reinforcement measures and expanding the arch foot, the vertical displacement of the surrounding rock decreases by 5.1% to 77.81%, and the maximum principal stress of the initial support decreases by 17.7% to 46.5%. From the reinforcement effect, it can be seen that the locking foot steel pipe pile reinforcement only improves the deformation of the arch foot surrounding rock and the stress on the lining, but the effect is not significant. Using enlarged arch feet in the lining structure can effectively control the deformation and stress of the lining structure, and the construction difficulty is small and the cost is low. The curtain grouting reinforcement has the best effect on improving the deformation and supporting structure stress of saturated loess tunnel surrounding rock after softening.
Under the action of groundwater, the surrounding rock of a loess tunnel will undergo varying degrees of softening, greatly weakening its strength, which brings many difficulties to the design and construction of the tunnel. Based on a loess tunnel in Longdong, different degrees of softening were set up, and finite element numerical simulation software was used to calculate and analyze the deformation of the tunnel surrounding rock and the stress changes of lining structure under different degrees of rock softening. At the same time, a comparative analysis was conducted on the on-site reinforcement measures after the softening of the surrounding rock and the lining structure of the enlarged arch foot. The results show that after the strong softening of the deeply buried loess tunnel, the settlement of the arch top increased by 271%, the uplift of the arch bottom increased by 283%, the horizontal convergence increased by 205%, and the maximum principal stress of the initial support increased by 107%. The most unfavorable stress position appeared at the arch shoulder. After adopting two reinforcement measures and expanding the arch foot, the vertical displacement of the surrounding rock decreases by 5.1% to 77.81%, and the maximum principal stress of the initial support decreases by 17.7% to 46.5%. From the reinforcement effect, it can be seen that the locking foot steel pipe pile reinforcement only improves the deformation of the arch foot surrounding rock and the stress on the lining, but the effect is not significant. Using enlarged arch feet in the lining structure can effectively control the deformation and stress of the lining structure, and the construction difficulty is small and the cost is low. The curtain grouting reinforcement has the best effect on improving the deformation and supporting structure stress of saturated loess tunnel surrounding rock after softening.
2024, 38(6): 698-703.
doi: 10.3969/j.issn.1007-2993.2024.06.009
Abstract:
The average shear wave velocity to a depth of 30 m below the ground surface （VS30） is an important parameter for evaluating the site condition and the site earthquake response. There are a large number of borehole data with depths of less than 30 m in China, and these borehole data cannot be directly used to calculate VS30 by definition equation code. Under this situation, referencing the correlated research results which include the parameter of VS30 were prevented. It is important to estimate VS30 accurately. Using the data of 590 boreholes with depths greater than 30 m in Guanzhong plain of Shaanxi Province to research the VS30 estimation model. The results show that the average shear wave velocity at different depths (Z<30 m) and the elevation of the borehole have a strong log-linear relationship with the measured value of VS30 along the depth, so a new model of log-linear extrapolation, which comprehensively considers the average shear wave velocity at different depths and the elevation of the borehole, was proposed. Compared with the velocity gradient extrapolation model and the double-depth parameter extrapolation model, when the calculation depth is smaller, the new model has higher estimation accuracy and better stability, and this advantage is more prominent.
The average shear wave velocity to a depth of 30 m below the ground surface （VS30） is an important parameter for evaluating the site condition and the site earthquake response. There are a large number of borehole data with depths of less than 30 m in China, and these borehole data cannot be directly used to calculate VS30 by definition equation code. Under this situation, referencing the correlated research results which include the parameter of VS30 were prevented. It is important to estimate VS30 accurately. Using the data of 590 boreholes with depths greater than 30 m in Guanzhong plain of Shaanxi Province to research the VS30 estimation model. The results show that the average shear wave velocity at different depths (Z<30 m) and the elevation of the borehole have a strong log-linear relationship with the measured value of VS30 along the depth, so a new model of log-linear extrapolation, which comprehensively considers the average shear wave velocity at different depths and the elevation of the borehole, was proposed. Compared with the velocity gradient extrapolation model and the double-depth parameter extrapolation model, when the calculation depth is smaller, the new model has higher estimation accuracy and better stability, and this advantage is more prominent.
2024, 38(6): 704-711.
doi: 10.3969/j.issn.1007-2993.2024.06.010
Abstract:
To study the influence of new pier construction on adjacent high-speed rail pier foundation, the whole construction process calculation model of the new pier was established based on the hardening soil model with small-strain stiffness (HSS model) and PLAXIS 3D finite element software, and then the soil displacement characteristics of adjacent existing high-speed rail pier foundation were analyzed. The reliability of the finite element model was verified by compared with the field monitoring data. The displacement of the pier and pile was calculated and analyzed. The results show that the HSS model is helpful to obtain more reliable displacement results in finite element calculation. In terms of soil mass, the maximum horizontal displacement and settlement are 1.53 mm and 5.49 mm in the horizontal direction of the foundation pit. The maximum settlement of the existing pier and cap is less than 6 mm, and the total settlement of the pier cap and the differential settlement of the adjacent pier cap is less than the standard limit. The outer top of the pile group of the existing pile foundation has a displacement to the four sides, while the top of the middle pile has a small settlement and bears the "open pattern" displacement state. During the construction of the new pier, the construction of the new bored pile, the insertion of the steel sheet pile, and the backfilling of the foundation pit have a great influence on the horizontal displacement and settlement of the existing high-speed railway pier foundation.
To study the influence of new pier construction on adjacent high-speed rail pier foundation, the whole construction process calculation model of the new pier was established based on the hardening soil model with small-strain stiffness (HSS model) and PLAXIS 3D finite element software, and then the soil displacement characteristics of adjacent existing high-speed rail pier foundation were analyzed. The reliability of the finite element model was verified by compared with the field monitoring data. The displacement of the pier and pile was calculated and analyzed. The results show that the HSS model is helpful to obtain more reliable displacement results in finite element calculation. In terms of soil mass, the maximum horizontal displacement and settlement are 1.53 mm and 5.49 mm in the horizontal direction of the foundation pit. The maximum settlement of the existing pier and cap is less than 6 mm, and the total settlement of the pier cap and the differential settlement of the adjacent pier cap is less than the standard limit. The outer top of the pile group of the existing pile foundation has a displacement to the four sides, while the top of the middle pile has a small settlement and bears the "open pattern" displacement state. During the construction of the new pier, the construction of the new bored pile, the insertion of the steel sheet pile, and the backfilling of the foundation pit have a great influence on the horizontal displacement and settlement of the existing high-speed railway pier foundation.
2024, 38(6): 712-717.
doi: 10.3969/j.issn.1007-2993.2024.06.011
Abstract:
A certain section of the Yechi Railway was affected by subgrade settlement disease. Through on-site geological investigation and analysis, it was found that the mining of coal seams changed the stress balance state of the surrounding strata, causing plastic deformation of the fault fracture zone along the F1 fault downwards, in addition, the Quaternary strata experienced drift sand along the fault, ultimately leading to subsidence and deformation of the ground. Based on the engineering situation, the treatment scheme of grouting in the Quaternary strata and grouting in fault zones was adopted to improve the mechanical properties of the Quaternary strata in the railway roadbed and enhance the plastic deformation resistance of the fractured zone. The characteristics of directional quantitative sizing and repeatability of sleeve valve pipe grouting were reflected by this plan. This scheme can provide a reference for similar projects.
A certain section of the Yechi Railway was affected by subgrade settlement disease. Through on-site geological investigation and analysis, it was found that the mining of coal seams changed the stress balance state of the surrounding strata, causing plastic deformation of the fault fracture zone along the F1 fault downwards, in addition, the Quaternary strata experienced drift sand along the fault, ultimately leading to subsidence and deformation of the ground. Based on the engineering situation, the treatment scheme of grouting in the Quaternary strata and grouting in fault zones was adopted to improve the mechanical properties of the Quaternary strata in the railway roadbed and enhance the plastic deformation resistance of the fractured zone. The characteristics of directional quantitative sizing and repeatability of sleeve valve pipe grouting were reflected by this plan. This scheme can provide a reference for similar projects.
2024, 38(6): 718-724.
doi: 10.3969/j.issn.1007-2993.2024.06.012
Abstract:
Based on the Suzhou Rail Transit Line 8 subway project, the synchronous grouting slurry was prepared using shield muck generated from soft clay stratum to reduce slag discharge. Based on lab testing, the strength, initial setting time, consistency, bleeding rate, etc. of the shield muck-produced grouting slurry were evaluated. Through engineering practice, the shield muck produced grouting slurry was used for grouting during shield excavation. The results show that the shield muck-produced grouting slurry met the performance requirements for synchronous grouting, and the performance of the muck-produced slurry could be improved by adjusting the mix ratio, demonstrating the feasibility of using soil pressure balance shield muck in soft soil strata to prepare synchronous grouting slurry. The slurry has been used for synchronous grouting during the excavation of the shield in the Suzhou Rail Transit Line 8 project, and the shield settlement and uplift value of lining segments are well controlled. Using shield muck for the preparation of grouting material can reduce the tunnel cost by approximately 750 thousand Yuan per kilometer and decrease the soil discharge by 10%, achieving considerable economic and environmental benefits.
Based on the Suzhou Rail Transit Line 8 subway project, the synchronous grouting slurry was prepared using shield muck generated from soft clay stratum to reduce slag discharge. Based on lab testing, the strength, initial setting time, consistency, bleeding rate, etc. of the shield muck-produced grouting slurry were evaluated. Through engineering practice, the shield muck produced grouting slurry was used for grouting during shield excavation. The results show that the shield muck-produced grouting slurry met the performance requirements for synchronous grouting, and the performance of the muck-produced slurry could be improved by adjusting the mix ratio, demonstrating the feasibility of using soil pressure balance shield muck in soft soil strata to prepare synchronous grouting slurry. The slurry has been used for synchronous grouting during the excavation of the shield in the Suzhou Rail Transit Line 8 project, and the shield settlement and uplift value of lining segments are well controlled. Using shield muck for the preparation of grouting material can reduce the tunnel cost by approximately 750 thousand Yuan per kilometer and decrease the soil discharge by 10%, achieving considerable economic and environmental benefits.
2024, 38(6): 725-731.
doi: 10.3969/j.issn.1007-2993.2024.06.013
Abstract:
The Hongtu extra-long tunnel is the key control project of the Dafenghua Expressway crossing Lianhua Mountain in Guangdong Province. The maximum buried depth of the tunnel is 740 m. In the process of tunnel excavation, a large flow of water was encountered under the pressure of 4.8 MPa, and the maximum water volume is 1.4×105 m3/d. By analyzing the influence of tunnel geological structure, the situation of high-pressure water inflow and its main water-conducting structure were expounded during the excavation process. At the same time, the water volume during the water inflow process was tracked, and the water quality of water inflow at different tunnel sections was compared. Three water storage structure modes, such as Tongziyang syncline water storage structure, rock mass intrusion contact water storage structure, and fracture fissure water storage structure, were proposed under the influence of the Lianhuashan fault in the Hongtu extra-long tunnel. Based on the relationship between the water inflow characteristics of the whole tunnel and the geological structure, it was proposed that the high-pressure water inflow mechanism of the tunnel was mainly affected by the horst-type hydrogeological model formed by the influence of the Lianhuashan fault, which makes the tunnel encounter high-pressure and large-flow water inflow during excavation. After penetration, it was controlled by the deep water storage cycle. After the stability of the groundwater system was rebuilt, nearly 60000 m3 large-flow water inflow per day is consistent with the actual situation.
The Hongtu extra-long tunnel is the key control project of the Dafenghua Expressway crossing Lianhua Mountain in Guangdong Province. The maximum buried depth of the tunnel is 740 m. In the process of tunnel excavation, a large flow of water was encountered under the pressure of 4.8 MPa, and the maximum water volume is 1.4×105 m3/d. By analyzing the influence of tunnel geological structure, the situation of high-pressure water inflow and its main water-conducting structure were expounded during the excavation process. At the same time, the water volume during the water inflow process was tracked, and the water quality of water inflow at different tunnel sections was compared. Three water storage structure modes, such as Tongziyang syncline water storage structure, rock mass intrusion contact water storage structure, and fracture fissure water storage structure, were proposed under the influence of the Lianhuashan fault in the Hongtu extra-long tunnel. Based on the relationship between the water inflow characteristics of the whole tunnel and the geological structure, it was proposed that the high-pressure water inflow mechanism of the tunnel was mainly affected by the horst-type hydrogeological model formed by the influence of the Lianhuashan fault, which makes the tunnel encounter high-pressure and large-flow water inflow during excavation. After penetration, it was controlled by the deep water storage cycle. After the stability of the groundwater system was rebuilt, nearly 60000 m3 large-flow water inflow per day is consistent with the actual situation.
2024, 38(6): 732-739.
doi: 10.3969/j.issn.1007-2993.2024.06.014
Abstract:
Southwestern China has become the most concentrated area for the construction of hydropower stations in China due to its rich hydropower resources. When building a hydropower station in the Alpine Valley area, it often causes the problem of destruction on steep rock slopes because of the excavation. To solve this problem, taking the No. 3 dangerous rock mass on the left bank slope of the Bowa Hydropower Station as the research object, combined with the 3D realistic modeling method of unmanned aerial vehicles, the deformation and failure modes and paths of the dangerous rock mass were qualitatively and quantitatively discussed using the stereographic projection method and limit equilibrium method. The results were analyzed and verified using numerical simulation methods. The main findings were as follows: The failure of No. 3 dangerous rock mass was mainly controlled by the preferred planes of both sides, belonging to a multi-stage and multiple wedge-shaped failure mode. It is relatively stable under natural engineering conditions, but it may occur under extreme conditions such as heavy rain and earthquakes. The numerical simulation results show a failure form of "sliding first and then dumping", which verifies the correctness of the theoretical analysis. Research results provide certain engineering experience and scientific reference value for similar steep rock slope problems of hydropower stations.
Southwestern China has become the most concentrated area for the construction of hydropower stations in China due to its rich hydropower resources. When building a hydropower station in the Alpine Valley area, it often causes the problem of destruction on steep rock slopes because of the excavation. To solve this problem, taking the No. 3 dangerous rock mass on the left bank slope of the Bowa Hydropower Station as the research object, combined with the 3D realistic modeling method of unmanned aerial vehicles, the deformation and failure modes and paths of the dangerous rock mass were qualitatively and quantitatively discussed using the stereographic projection method and limit equilibrium method. The results were analyzed and verified using numerical simulation methods. The main findings were as follows: The failure of No. 3 dangerous rock mass was mainly controlled by the preferred planes of both sides, belonging to a multi-stage and multiple wedge-shaped failure mode. It is relatively stable under natural engineering conditions, but it may occur under extreme conditions such as heavy rain and earthquakes. The numerical simulation results show a failure form of "sliding first and then dumping", which verifies the correctness of the theoretical analysis. Research results provide certain engineering experience and scientific reference value for similar steep rock slope problems of hydropower stations.
2024, 38(6): 740-744.
doi: 10.3969/j.issn.1007-2993.2024.06.015
Abstract:
A comprehensive geotechnical investigation was conducted at a construction project site on Hainan Island. Specific geotechnical parameters of volcanic ash deposits in high-order areas and volcanic rock plateaus in northern Hainan Island were summarized. The distinct engineering characteristics of this unique soil and rock type were investigated. A multi-faceted approach was employed, including on-site drilling, standard penetration tests, seismic velocity tests, laboratory soil physical-mechanical experiments, optically stimulated luminescence tests, X-ray fluorescence semi-quantitative analysis, and mineral X-ray diffraction analysis. The depositional origin and era of these deposits were examined. Furthermore, recommended values for fundamental engineering characteristic parameters were proposed, providing a solid foundation for the utilization and foundation treatment of this soil type, thereby reducing engineering risks.
A comprehensive geotechnical investigation was conducted at a construction project site on Hainan Island. Specific geotechnical parameters of volcanic ash deposits in high-order areas and volcanic rock plateaus in northern Hainan Island were summarized. The distinct engineering characteristics of this unique soil and rock type were investigated. A multi-faceted approach was employed, including on-site drilling, standard penetration tests, seismic velocity tests, laboratory soil physical-mechanical experiments, optically stimulated luminescence tests, X-ray fluorescence semi-quantitative analysis, and mineral X-ray diffraction analysis. The depositional origin and era of these deposits were examined. Furthermore, recommended values for fundamental engineering characteristic parameters were proposed, providing a solid foundation for the utilization and foundation treatment of this soil type, thereby reducing engineering risks.
2024, 38(6): 745-749.
doi: 10.3969/j.issn.1007-2993.2024.06.016
Abstract:
Bilateral Helix-Stiffened Cement Mixing Piles (BHCMP) is a new type of stiff composite pile. To study the feasibility of the construction process and the compressive bearing performance of BHCMP, three test piles were designed, and the on-site pile formation test and the compressive bearing performance test of the pile foundation were conducted. Comparative analysis of the pile forming process and bearing properties of helical piles, helical stiffened cement mixing piles, and BHCMP was carried out. The test results show that: the vertical bearing capacity of the helical pile is improved by synchronized rotary grouting around the helical pile to form a hydraulic soil column, which is about 1.85 times that of the helical pile, while the BHCMP has a 49% increase in ultimate compressive bearing capacity compared with the helical stiffened cement mixing piles through the secondary mixing and downward drilling, which makes the mixing of silt soil and cement in the re-drilled section more adequate and forms a hydraulic soil column with higher strength.
Bilateral Helix-Stiffened Cement Mixing Piles (BHCMP) is a new type of stiff composite pile. To study the feasibility of the construction process and the compressive bearing performance of BHCMP, three test piles were designed, and the on-site pile formation test and the compressive bearing performance test of the pile foundation were conducted. Comparative analysis of the pile forming process and bearing properties of helical piles, helical stiffened cement mixing piles, and BHCMP was carried out. The test results show that: the vertical bearing capacity of the helical pile is improved by synchronized rotary grouting around the helical pile to form a hydraulic soil column, which is about 1.85 times that of the helical pile, while the BHCMP has a 49% increase in ultimate compressive bearing capacity compared with the helical stiffened cement mixing piles through the secondary mixing and downward drilling, which makes the mixing of silt soil and cement in the re-drilled section more adequate and forms a hydraulic soil column with higher strength.
2024, 38(6): 750-753.
doi: 10.3969/j.issn.1007-2993.2024.06.017
Abstract:
Recharge is one of the effective measures to protect groundwater resources in urban construction. To reasonably consider the influence of group well effect in the design of a recharge project, the influence of group well effect on the recharge capacity of a single well was experimentally studied by adjusting the number and spacing of recharge wells dynamically in the selected recharge area, and the change law of the recharge capacity of a single well with the number and spacing of recharge wells was summarized. The results show that the group well effect has a significant effect on the recharge capacity of a single well. Once the recharge area is selected, the recharge capacity of a single well decreases with the increase of the number of recharge wells, and the relationship between the recharge capacity of a single well and the spacing of recharge wells is roughly logarithmic.
Recharge is one of the effective measures to protect groundwater resources in urban construction. To reasonably consider the influence of group well effect in the design of a recharge project, the influence of group well effect on the recharge capacity of a single well was experimentally studied by adjusting the number and spacing of recharge wells dynamically in the selected recharge area, and the change law of the recharge capacity of a single well with the number and spacing of recharge wells was summarized. The results show that the group well effect has a significant effect on the recharge capacity of a single well. Once the recharge area is selected, the recharge capacity of a single well decreases with the increase of the number of recharge wells, and the relationship between the recharge capacity of a single well and the spacing of recharge wells is roughly logarithmic.
2017, 31(3): 153-159,163.
doi: 10.3969/j.issn.1007-2993.2017.03.010
摘要：
将边坡稳定性分析的方法分为确定性分析方法(以瑞典圆弧法、简化Bishop法等为代表的极限平衡法和以有限元法、有限差分法等为代表的数值分析方法)和非确定性方法(可靠度法、模糊综合判断法、灰色系统法、人工智能法等),详述了各分析方法的原理、优缺点以及适用性,并对其中一些方法进行了比较分析,提出了岩土边坡系统稳定性评价的发展方向。
将边坡稳定性分析的方法分为确定性分析方法(以瑞典圆弧法、简化Bishop法等为代表的极限平衡法和以有限元法、有限差分法等为代表的数值分析方法)和非确定性方法(可靠度法、模糊综合判断法、灰色系统法、人工智能法等),详述了各分析方法的原理、优缺点以及适用性,并对其中一些方法进行了比较分析,提出了岩土边坡系统稳定性评价的发展方向。
2020, 34(3): 143-149.
doi: 10.3969/j.issn.1007-2993.2020.03.005
摘要：
有限元软件数值模拟是现在从业人员分析敏感环境下基坑工程的重要手段，选择合适的本构模型是其关键。为了解工程中常用的三种土的本构模型适宜性，运用三维有限元软件Midas GTS NX模拟了某大型深基坑开挖过程，将采用不同本构模型的数值模拟结果与基坑监测结果进行对比，进而分析本构模型的适用性。可为本区类似工程进行有限元数值模拟分析时提供参考和借鉴。
有限元软件数值模拟是现在从业人员分析敏感环境下基坑工程的重要手段，选择合适的本构模型是其关键。为了解工程中常用的三种土的本构模型适宜性，运用三维有限元软件Midas GTS NX模拟了某大型深基坑开挖过程，将采用不同本构模型的数值模拟结果与基坑监测结果进行对比，进而分析本构模型的适用性。可为本区类似工程进行有限元数值模拟分析时提供参考和借鉴。
2016, 30(2): 85-88.
doi: 10.3969/j.issn.1007-2993.2016.02.007
摘要：
BIM技术具有三维可视化、碰撞检测、工程信息管理等众多特点,极大地提升了工程质量与效率,在建筑领域得到迅猛发展,然而在岩土工程中因为收费机制、软件功能限制、应用局限性等原因导致其发展的严重滞后。随着设计可视化、信息化发展进程,BIM也将在岩土中得到立足。对BIM在岩土中的应用现状进行了剖析,并对发展前景展望。以武汉亚洲医院基坑项目为依托,进行了BIM的完整实施,探讨了模型建立方式与施工应用方法,对今后BIM在岩土工程中的应用推广具有一定指导意义。
BIM技术具有三维可视化、碰撞检测、工程信息管理等众多特点,极大地提升了工程质量与效率,在建筑领域得到迅猛发展,然而在岩土工程中因为收费机制、软件功能限制、应用局限性等原因导致其发展的严重滞后。随着设计可视化、信息化发展进程,BIM也将在岩土中得到立足。对BIM在岩土中的应用现状进行了剖析,并对发展前景展望。以武汉亚洲医院基坑项目为依托,进行了BIM的完整实施,探讨了模型建立方式与施工应用方法,对今后BIM在岩土工程中的应用推广具有一定指导意义。
2016, 30(1): 6-11.
doi: 10.3969/j.issn.1007-2993.2016.01.002
摘要：
探讨了BIM在岩土工程勘察领域应用的可行性,根据多年的研究和工程实践,提出了BIM技术应用于岩土工程勘察领域的目标、实现途径和分阶段的解决方案。
探讨了BIM在岩土工程勘察领域应用的可行性,根据多年的研究和工程实践,提出了BIM技术应用于岩土工程勘察领域的目标、实现途径和分阶段的解决方案。
2016, 30(1): 12-19,38.
doi: 10.3969/j.issn.1007-2993.2016.01.003
摘要：
黄土丘陵沟壑区高填方工程的地形地貌和地质环境复杂,场地内常分布有大面积湿陷性黄土和淤积土,且具有土方量大、影响因素多、施工工期紧、沉降控制要求高等特点,建设过程面临着填方体的稳定、变形、排水、湿化变形控制及边坡防护等问题。以国内几处典型黄土高填方工程为例,介绍了通过场地综合地质条件评价、土方平衡优化、地下盲沟排水、原地基强夯加固处理、填筑体压(夯)实处理、填挖边坡防护处理、施工质量立体式监控、岩土工程全程监测等多种手段有效组合,解决黄土高填方工程问题的实践工作,相关经验可供类似工程借鉴。
黄土丘陵沟壑区高填方工程的地形地貌和地质环境复杂,场地内常分布有大面积湿陷性黄土和淤积土,且具有土方量大、影响因素多、施工工期紧、沉降控制要求高等特点,建设过程面临着填方体的稳定、变形、排水、湿化变形控制及边坡防护等问题。以国内几处典型黄土高填方工程为例,介绍了通过场地综合地质条件评价、土方平衡优化、地下盲沟排水、原地基强夯加固处理、填筑体压(夯)实处理、填挖边坡防护处理、施工质量立体式监控、岩土工程全程监测等多种手段有效组合,解决黄土高填方工程问题的实践工作,相关经验可供类似工程借鉴。
3D Laser Scanning Technology and BIM Technology in Ancient Building Protection Surveying and Mapping
2019, 33(4): 222-225.
doi: 10.3969/j.issn.1007-2993.2019.04.008
摘要：
结合北京市密云区古北口村文物建筑群工程实例介绍了三维激光扫描技术、BIM（建筑信息模型）在古建筑测绘中的应用。通过对比传统测绘方法，证明其在测绘及文物保护方面应用的优势。
结合北京市密云区古北口村文物建筑群工程实例介绍了三维激光扫描技术、BIM（建筑信息模型）在古建筑测绘中的应用。通过对比传统测绘方法，证明其在测绘及文物保护方面应用的优势。
2018, 32(4): 189-193,198.
doi: 10.3969/j.issn.1007-2993.2018.04.006
摘要：
上海市城市道路发生的地面塌陷主要原因为浅部砂层分布区域地下排水管线渗漏引发流砂,导致地下土体流失,地表硬壳层承载力下降。将有限元和离散元二者进行耦合,从管线渗漏位置和对邻近管线影响两个方面诱发地下空洞机理进行数值模拟研究。研究结果表明,管道表面顶部局部渗漏引起地表以下土体流失量最大,底部渗漏造成的影响范围较小;管道断裂渗漏引起的地面塌陷范围比管道局部渗漏大得多,但深度较管道顶部局部渗漏引起的塌陷深度小;邻近管道埋深越大,地表以下土体流失量越大,引起塌陷影响区域范围越大,而埋深较浅时,其所受邻近渗漏管道的影响较大;在对地面塌陷进行监测与预防时,不应仅关注地表沉降变形,关注管道周边的土体变形是一种更加及时有效的方法。
上海市城市道路发生的地面塌陷主要原因为浅部砂层分布区域地下排水管线渗漏引发流砂,导致地下土体流失,地表硬壳层承载力下降。将有限元和离散元二者进行耦合,从管线渗漏位置和对邻近管线影响两个方面诱发地下空洞机理进行数值模拟研究。研究结果表明,管道表面顶部局部渗漏引起地表以下土体流失量最大,底部渗漏造成的影响范围较小;管道断裂渗漏引起的地面塌陷范围比管道局部渗漏大得多,但深度较管道顶部局部渗漏引起的塌陷深度小;邻近管道埋深越大,地表以下土体流失量越大,引起塌陷影响区域范围越大,而埋深较浅时,其所受邻近渗漏管道的影响较大;在对地面塌陷进行监测与预防时,不应仅关注地表沉降变形,关注管道周边的土体变形是一种更加及时有效的方法。
2019, 33(2): 84-88.
doi: 10.3969/j.issn.1007-2993.2019.02.006
摘要：
总结分析了建筑工程肥槽回填土质量不良引发的常见工程问题，以及肥槽回填土不易施工密实的几个主要原因，并总结提出了各种肥槽回填土处理方法，以及它们主要的适用条件。
总结分析了建筑工程肥槽回填土质量不良引发的常见工程问题，以及肥槽回填土不易施工密实的几个主要原因，并总结提出了各种肥槽回填土处理方法，以及它们主要的适用条件。
2019, 33(2): 115-120.
doi: 10.3969/j.issn.1007-2993.2019.02.013
摘要：
针对珠海地区的深厚软基，采用真空联合堆载预压法进行加固处理。在施工过程中对软基的地表沉降、膜下真空度、孔隙水压力、深层水平位移等进行监测，得到了真空预压加固软土地基的随时间变化曲线。软基处理完成后对原状土进行原位十字板剪切试验和载荷试验，并取土进行室内土工试验。监测和检测试验分析表明：加固后土的物理力学性质有了明显提高，地基加固效果较好，其影响深度达到25～30 m，在15～20 m范围内加固效果最为显著; 但真空预压并未改变软土的触变性，加固后的软土仍应避免扰动。
针对珠海地区的深厚软基，采用真空联合堆载预压法进行加固处理。在施工过程中对软基的地表沉降、膜下真空度、孔隙水压力、深层水平位移等进行监测，得到了真空预压加固软土地基的随时间变化曲线。软基处理完成后对原状土进行原位十字板剪切试验和载荷试验，并取土进行室内土工试验。监测和检测试验分析表明：加固后土的物理力学性质有了明显提高，地基加固效果较好，其影响深度达到25～30 m，在15～20 m范围内加固效果最为显著; 但真空预压并未改变软土的触变性，加固后的软土仍应避免扰动。
2017, 31(6): 306-310.
doi: 10.3969/j.issn.1007-2993.2017.06.009
摘要：
以某一地下一~二层连通车库基坑设计项目为依托,在分析该基坑工程特点的基础上,介绍和分析了不同开挖深度和复杂环境条件下的多种基坑支护形式的组合应用和监测结果,为今后类似工程提供一些借鉴和参考。
以某一地下一~二层连通车库基坑设计项目为依托,在分析该基坑工程特点的基础上,介绍和分析了不同开挖深度和复杂环境条件下的多种基坑支护形式的组合应用和监测结果,为今后类似工程提供一些借鉴和参考。
2021, 35(4): 269-274.
doi: 10.3969/j.issn.1007-2993.2021.04.012
Abstract:
2021, 35(1): 1-6,11.
doi: 10.3969/j.issn.1007-2993.2021.01.001
Abstract:
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